More on Not Worth a Rap from Infoplease:

• Not Worth a Rap - Not Worth a Rap (See Rap.) Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894 Related ...
• Dam - Dam An Indian copper coin, the fortieth part of a rupee. Hence the expression “Not worth a ...
• Rap - Rap Not worth a rap. The rap was a base halfpenny, intrinsically worth about half a farthing, ...
• Straw - Straw Servants wishing to be hired used to go into the market-place of Carlisle (Carel) with a ...
• Dictionary of Phrase and Fable: N - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "N"